代码：

#include <stdlib.h>
#include <stdio.h>
typedef struct Node
{char data;struct Node *lchild;struct Node *rchild;
}*Tree;
//申请空间
Tree create_space()
{Tree t = (Tree)malloc(sizeof(struct Node));if(NULL == t){return NULL;}t->data = 0;t->lchild = t->rchild = NULL;return t;
}
//创建二叉树
Tree create_tree()
{printf("please write character:\n");char ch;scanf(" %c", &ch);if('#' == ch)return NULL;Tree t = create_space();t->data = ch;t->lchild = create_tree();t->rchild = create_tree();return t;
}
//销毁
void destroy_tree(Tree t)
{if(NULL == t)return;destroy_tree(t->lchild);destroy_tree(t->rchild);free(t);t = NULL;
}
//先序遍历
void first_output(Tree t)
{if(NULL == t)return;printf("%c", t->data);first_output(t->lchild);first_output(t->rchild);
}
//中序遍历
void mid_output(Tree t)
{if(NULL == t)return;first_output(t->lchild);printf("%c", t->data);first_output(t->rchild);
}
//后序遍历
void last_output(Tree t)
{if(NULL == t)return;first_output(t->lchild);first_output(t->rchild);printf("%c", t->data);
}
int main(int argc, const char *argv[])
{Tree t = create_tree();printf("先序遍历:\t");first_output(t);puts("");printf("后序遍历:\t");mid_output(t);puts("");printf("中序遍历:\t");last_output(t);puts("");destroy_tree(t);return 0;
}

效果图：